Early
in the third season, Prado presented Dexter with his white shirt, supposedly
stained with the blood of Freebo (whom
Dexter had killed), as proof of that he could be trusted to keep Dexter's
secret. The bloody shirt could presumably be used as evidence against Prado,
connecting him to the murder.

Later,
however, as Dexter and Prado had a falling out, Dexter had the blood tested
and determined that it was cow's blood.

Enraged
that Prado had fooled him, and still chafing
at Prado's attempt to blackmail him at the donut
shop, Dexter goes to Prado's house and steals the ring that Prado took
(as a souvenir) from the dead finger of Ellen Wolf, a defense attorney
that Prado murdered. It is the piece of conclusive evidence that Dexter
needs to keep Prado in line. In its place, Dexter left a receipt from a
cleaners.

Prado
(who has come home to find the ring missing and the receipt in its place)
anxiously hurries to the cleaners and redeems the ticket. The woman behind
the counter brings out the white shirt he had given Dexter, still stained
with blood. She explains to him that they tried, but that the blood just
wouldn't come out - a not-so-subtle message from Dexter that he knows that
Prado has conned him about the shirt, and that he has now one-upped him.

A. In real life,
it is Sir Richard's
Cleaners, at 233 W. 4th Street,in Long Beach, CA.
It fronts the north side of 4th Street, between Pacific & Cedar,
at the northwest corner of an alley (named Park Ct) and 4th St.

The
cleaners is right across the alley from (southwest of) the supermarket
(where Dexter first encounters the child stalker) and is across the street
from (northwest of) the donut shop (where
Prado threatened Dexter).

[
Be warned that this is a slightly scruffy
part of town, so exercise reasonable caution if you visit.
]

A. After
finding both the supermarket and the donut
shop, from the same episode 10, I had a hunch that they might have
shot the cleaners here too. So I simply checked for cleaners in the same
neighborhood. When I found Sir Richard's right next to the other two locations,
I used Google StreetView to take a closer look and match the details,
then later drove there in person and shot the photo you see above.

And
sure enough, not only did the view across the street match, this cleaners
even had the same sign painted on the window .